If you thought Wall Street had learned its lesson four years after the global financial crisis, JPMorgan Chase's $2 billion trading debacle suggests you should think again, investment bankers and industry experts say.

To some, it suggests that the need for financial reform is still just as urgent as it was the day the crisis broke out.

JPMorgan revealed on Thursday that it had lost about $2 billion (with possibly more losses to come) from risky bets on opaque derivatives at a London trading desk.

JPMorgan's big losing trade shows that at least some big banks are engaged in the same sort of behavior that rocked the financial system in 2008, if on a smaller scale.

“This is a smaller version of the same betting that went on in 2006,” said Will Rhode, a principal and director of fixed income at The Tabb Group, a financial-markets research and advisory firm.

“Ultimately, this is about banks being dissatisfied with the single-digit returns on equity that are associated with their conventional lending businesses, and trying to find other ways to make money," said Daniel Alpert, founding managing partner at investment bank Westwood Capital, "with risk, once again, taking a backseat to potential reward.”

The episode has provided ammunition to those calling for new regulations, particularly the part of the Dodd-Frank financial reform act known as the Volcker Rule, or a ban on proprietary trading by federally insured banks. The rule is currently scheduled to take effect in July, though Federal Reserve Chairman Ben Bernanke has suggested regulators will probably miss the deadline. Part of the delay is due to a barrage of pressure from lobbyists, who have helped to complicate and water down the rule.

“This latest debacle at JPMorgan demonstrates that the banks cannot police themselves, and should not be trusted to do so,” said law professor Frank Partnoy, director of the Center on Corporate and Securities Law at the University of San Diego. “At minimum, they should be required to disclose details about their derivatives, so their shareholders can understand what risks they are taking.”

By Friday afternoon, lawmakers were starting to make a similar argument.

“If the regulators do what [the Volcker rule] says ... this activity would not be permitted,” Sen. Carl Levin (D-Mich.), one of the authors of the Volcker rule, told CNBC. “The purpose of Dodd-Frank was essentially to bring back a cop on the beat on Wall Street.”

Tabb Group’s Rhode went further.

“This makes the Volcker rule a foregone conclusion,” he said. “The entire financial community is holding their heads in their hands saying this JPMorgan event could not have happened at a worse time.”

The fact that the trading losses happened at JPMorgan, whose CEO, Jamie Dimon, has been an outspoken critic of financial reform, likely strengthens the argument of those pushing for more regulation.

"There's something delicious about this happening to JPMorgan," Rep. John Sarbanes (D-Md.) told The Huffington Post on Friday.

JPMorgan's troubles should help Dodd-Frank's cause, said Sarbanes, the son of former Sen. Paul Sarbanes (D-Md.), who co-sponsored the Sarbanes-Oxley financial regulation law that passed in 2002.

However, "people forget quickly," he cautioned. "The finance industry has a lot of sway."

What is difficult to tell is exactly how widespread the practices are that got JPMorgan into trouble -- partly because without financial reforms, the riskier corners of Wall Street are still just as murky as they were before the crisis.

“We never hear about these things if they profit from it," said William D. Cohan, a former managing director at JPMorgan who now writes frequently about the banks. "They never call a five o’clock press conference saying we made $4 billion on a London Whale trade.

"We’ll never know who else is doing it, and this is one of the big problems," he added. "It’s an opaque black box.”

The JPMorgan incident also highlights one other problematic trend still lingering from the crisis: Too-big-to-fail banks engaging in risky behavior that could possibly lead to government bailouts.

"We have to decide whether we want these banks to be large public utilities -- very safe, not generating humongous returns," said Alpert of Westwood Capital, "or do we want these institutions to engage in speculation and put our system at risk?”